Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of the first image in a sequence for a displayscreen or portion thereof with transitional graphical user interface,showing our new design;

FIG. 2 is a front view of second image thereof;

FIG. 3 is a front view of third image thereof;

FIG. 4 is a front view of fourth image thereof;

FIG. 5 is a front view of fifth image thereof;

FIG. 6 is a front view of sixth image thereof;

FIG. 7 is a front view of seventh image thereof;

FIG. 8 is a front view of eighth image thereof;

FIG. 9 is a front view of ninth image thereof;

FIG. 10 is a front view of tenth image thereof;

FIG. 11 is a front view of eleventh image thereof;

FIG. 12 is a front view of twelfth image thereof; and,

FIG. 13 is a front view a second embodiment thereof.

The dot-dash broken line showing of an electronic device and displayscreen form no part of the claimed design. The remaining broken lines,illustrating portions of the graphical user interface, form no part ofthe claimed design.

The appearance of the image transitions sequentially between the imagesshown in FIGS. 1 through 12. The process or period in which one imagetransitions to another forms no part of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof withtransitional graphical user interface, as shown.